Balancing system for aircraft



J. P. TARBOX BALANCING SYSTEM FOR AIRCRAFT Filed March 20. 1924 I5 Sheets-Sheet l .1. P. TARBOX BALANCING SYSTEM FOR AIRCRAFT Filed March 20. 1924 3 Sheets-Sheet 3 IN V EN TOR ill ill

Patented ct. ll, u

JOHN P. TARBOX, OF GARDEN CITY, NEW YORK, ASSIGNOR T0 TARBOX SAFETY .Mllw CRAFT COMPANY, 0]! WASHINGTON, DISTRICT OF COLUMBIA, A. COMPANY 0H. @thl lIZliilD UNDER THE LAWS 013 DELAWARE.

BAILANGING SYSTEM FOR .AllItCRAF'lI.

Application filed March 20, 1924. Serial No. 700,503.

lvly invention relates particularly to let oral balancing systems for aircraft, but While of that particular relation may also have some adaptation to the longitudinal balance of aircraft and directional steering. Still more particularly the invention relates to those lateral balancing systems employing ditl'ercntial selt-acting lateral balance control surfaces of the type disclosed.

Referring to the drawings:

Fig. 1 is a diagrammatic perspective of the system; a

Fig. 2 is sheet oi graphsillustrating the characteristics oil the control surfaces employed;

l ig. 3 is a diagrammatic perspective of a modification of the system;

Fig. alis a perspective oil a turther modification and Fig. a perspective of still a third modilication.

Referring first to Fig. .i. The dotted sur face 10 represents diagrammatically the principal supporting surface of the aeroplane. As lateral extensions of this surface are right and left ailerons lit, L, respectively. The ailerons are mounted on axes All. related fixedly to the principal supporting surt'ace 10 in any suitable structural manner. From this standpoint ailerons lit, L need not necessarily be in lateral extension of the principal supporting surface 10 but may bear any positional relation thereto compatible with convenient location of the axes. Thus they might be located between biplane Wings. The relation is not essential tho important.

ailerons lit, L are interconnected by a continuous cable (3 C or its equivalent to partake of movement in o posit/e directions when the cable is moved. 1 ornially the aile none are set at an angle in which they lift substantially and to this extent are part and parcel of the aggregate lifting surface oil the aeroplane. we set, when moved oppositely they are also moved differentially in an acre-dynamic sense, the lift ol one being increased while the lift of the other is decreased.

ln Fig. 2, l have disclosed the characteristics which it embody in these ailerons. These are. of course, to be taken as illustrative oil the general characteristics which it give the ailerons of the system. These graphs show the lift K the drift K, the ratio of lift to drift K K, and the center of pressure travel Cl characteristics of an aorotoil section known as Eiil'el #32. With this section when the axes AA of the ailerims are located on a line 25 per cent of the chord from the leading edge, being related to the center of pressure travel of the aero foil in the manner shown in the graph by the dash and dot line marked All, the net torque of ailerons R, L about their axes All, progressively. regularly and uniformly in creases. This is shown on the graphs by the torque curve labeled TC which is plotted the net of the lift coeilioient lil multiplied by the percent travel of the center of pressure of the aerofoil Cl from the axis line AA, a factor proportional to actual axial torque. It is also proportional to the pitch ing moment about AA. The ailerons are assumed to have been set in a normal position of 6, but it is equally true of other normal settings, for example 1 9, 4%" ctcw Within a determinate range.

Thenct torque is the algebraic difference between the torque of the aileron Whose incideuce is increased and thatoi? the aileron Whose incidence is decreased. Thus for can ample, when the incidence! of one aileron is increased 2 from 6 to 8 and that of the other is differentially decreased from 6 to 4, the net torque expressed in the units selected is indicated by curve TC to be about 4.33. It will be noted that curve T0 is a very smooth curve, the increase being not only regular but so uni-form that the curve approximates a straight line.

A. number of aerot'oil sections markedly showing these general characteristics exist at the present time and others will be de vised as the art progresses.

Preferably within the body ot the aeroplane is a lever B pivoted on a vertical axis V carried on a forward entension oil the rudder bar B, and extended forwardly beyond the vertical line or vertical transverse plane passing thru the center of gravity CG. At or near its forward end this lever carries an adjustable weight W Whicl'i is located as far forward of the center oi gravity CG as convenient space will per mit. l'iever E is connected with branch C of the differential cable (3 ll at a point between weight W and aain llhi lltitl lea Gonnected with branch C of the cable are a pair of vanes N N one to the leftand one to the right. These vanes are supported on vertical axes in such manne r that when subjected to side pressure they operate to tend to pull cable G in a direction to increase the incidence of the ileron L which lies on the side of the aeroplane from which the side pressure comes. Varies N N lie aft of the transverse plane passing thru the center of gravity They may he conveniently hinged any or the rear struts, as for example, e rear intermediate struts of biplane raulti-nlane, supported on some indendent aires in a incnoplane, singly or cornned, or 7' other convenient noint,

I? also connects With manual cona control mechanism or the orov ded i; and an eievator the usual (not l is follows:

ht ahead struck direction l, Aileron is in tins manner ageinent with this act of e done Work or"- hoclr absorbers in ctive tor 3 J are the nee-arse jected to side pressure in combined proportion to such acceleration and any veering Which may take place either as a result of such acceleration or difference in drag between opposite sides of the machine, or both of these factors together. But, gravity and side pressure act thru the weight and vanes respectively upon cable C in conjunction, which is to say, they tend to move the ailerons R in the same direction and this direction is that which increases the incidence oi aileron L on the low left side of the machine (st-ill assuming the gust shown in g. 1). Together thegravity and side p essure forces are greater toan any other rce set up in the system by virtue of i eral acceleration of the aeroplane at large. Barring friction the gravity acceleration of W will always exceed that of the aeroplane at large, because the large vertical surfaces of the aeroplane retard it. Thus When roll ensues the advance move rnent of die ailerons ust described is sunpleinented new by a iurther movement proporticnai to degree 0 roll. We may say that the advance setti of the ailerons is proportional to the gust as reoresented by ailerons are in 13051 corrective to one "oro oor Work of as presentin a i the en ire t dev *1 rie'veloned mamas cause of most unhalancinc'. In making it predominant we strike that cause at its root. As Weight W normally swings in a horizontal plane it does not in any way interfere with that predominance except to the extent of its inertia. of movement, and therefore the initial shock absorbing and counteracting action of theailerons under the impact of the gust is not interferred with by gravity, nor by thesubordinated vanes l N. The initial response of the system, is therefore, very quick and very full.

Because extreme gusts should be counteracted at their inception as far as may be, it is provided that the rust torque on a given aileron may move the system to its extreme limit. Suitable limit stops are provided to detine this. (See Fig. 2). Because the rust torque may so move the system, and because it always moves or tends to move the system to some extent at least be- ."t'ore roll sets in, the gravity torque of W is used in supplementation merely, and sufiiciently to be eilective after the gust has passed to insure prompt return of the craft to normal. position.

The vanes Ni, ll are but required to overcome friction and accelerate the system in the right direction under side pressure, and to assist the ailerons in damping its movement. The weather vane action by which it'assists the ailerons in centering" the system and establishing a determinate normal for "weight i i must be overcome both by weight W and the ailerons under gust torque. Ubyiously vanes N8, N" develop a subordinated torque.

The action oi. turning is simple. One merely operates the loot bar l in the usual manner. This operation thru connection V the ailerons an initial movement to i itiate bank. and swings the aeroplane (lily about its vert cal axis so that the rrush is from a quarter. Such progress of are airplane is called sl'ciddin x, and is really lateral acceleration. (this swinging; by virtoe o the inertia of weight ahead oi the l /G and the n action of vanes hi N behind the CG it "ease the initial movement or the ailerons. h swinging ot the aeroplane, however, s but momi diately', due to he vertical aeroplane at l:

plus the initiated bank, the craft commences to turn about an imaginary point in space. The moment it eomfinances to t rn centrifugal torce acts upon weight is centrii ugal force con joined with the force oi the uuartering airrush on vanes ll it-- due to the lateral acceleration operates to swine; weight W outwardly to increase the already greater incidence oi the aileron on the outer side ot' the ueroulane and correspondingly decrease the incnence on inner side or the aeroplane to tut-their banli the craitt. the craft comes up into a bank the turning action is accentuated and the relative wind returns quickly toward the head, cutting down the force exerted by vanes NE, N while the centrifugal force for the moment accentuated raising the force on weight /V. As the areoplane banks up, however, gravity comes into play tending: to carry weight \V back to its normal position, and this it does do as the craft pulls up into steady flight at the proper bank. At this point the rudder is released to a degree compatible with the flying; characteristics of the aeroplane and may be taken off altogether, should the aeroplane hold its turn without it. 'lhereafter the aeroplane behaves in bani; precisely as it 'does on straight-away flight responding to gusts in the same manner. To come out of the turn, one has but to apply reversed rudder. Centrifugal force is at once abated. Grav ty and whatever slight side slip (or lateral acceleration toward the a low side) there is apply the aileron on the low side and the ship is progressively relieved oi its bank.

By virtue of the characteristics given ailerons R. L set forth in Fig. 2, whenever they respond to an air gust that response is not only prompt but very accurately proportional to the force of the gust. This cannot be otherwise when the curve of net torque of ailerons R, ll is formed as set forth. The proportion is the more exact the more uniform the pitching moment curve of the section. Moreover, the supplemental move ment of the ailerons when the aeroplane rolls is most accurately proportional to the supplementing forces of gravity and side pressure as imposed thru weight W and vanes N. The torque oi e'ravity as developed thru wei ight W in cable C is progressively, regularly, and substantially uniformlydeveloped along a sin cos curve whichapproximates very closely that curve oi net torque of the ailerons outlined in Fig. 2. Thus each degree of roll bringing ahoutan increased movement oi weight "W and an in creased gravity torque in cable C C .tincls a complemental opposition developed by the net torque of the microns in the same cable. The action is resultingly not only most accurate but highly dead-beat.

But a yet greater advantage results from this combination. Differentially acting ailerons whose not torques progressively in crease in the manner specified, regularly or uniformly as the case may be are etl'cctive thru a much greater range at dying angles than those which do not possess these characteristics. in tact they effective tl'irougliout the entire range oil illyinfr angles of any aeroplane upon which the system is installed. lly etlective' is meant the capability oit developii'ig adequate corrective torque to preserve lateral balance. In other words,

' he tal on Uncle"; automatic control the "Wheel of the cont mechanism is revolvecl hack and rorth by the movement ot the cable over uruin. Elevating control during this p riotl is means of an auxiliary hancl grip G, At any moment the manual con trol he assumed by merely shitting ones hancl om in G to the Wheel H. This consta aveila'le manual control is one of in launchtne a es of this system. mg or or in any close space, or at any other time it is 'olesirecl execute an unus ueuver, manual control may he risen nerely icy grasp' the Wheel. There are no auxil ary levers, clutches, or

like s m n y appurtenances which v0 0 reluuinaruy manipulateo, 'Uh any unnecessary loacl can the-Wheel vvi v he is using control and; increases ease of manual control of the I l one or the greatest clravr in system this is r rt t J ant rictiou hear "7 ect cable connections throughie system especially lent ls itself to cahle connections, ll urther the vanes acted upon toy sicle pressure overcome We mains oi friction, importantly in gram my clevelcpecl nnnor acceleration of the aeroplane large, luring which triction ii enough. tends to preclude acceleration of in response to the :t'orce oi gravity, vanes N N are inatle oi the largest rracticshle area cons stent with the preclon once of vveig' *I or ailerons ll ancl la, the case he. lln other vvorcls, they are made just as large as it is possible to i them ithout permitting them when rle ctecl to uncluly oppose the aileron 'inovei out resulting from either airrush or for vanes N l l as hereinloetore set lnv also to damp this system by virtue their vvinrl vane act-ion; llhereailerons anti in preservinc the a i heat operation.

to amount of friction in a sysvcr, also tlepencls upon the magnilorces which its relatively movllase oi"- nsanipulation is also tly' upon the magnitude of is part of my tulle of these forces to a minimum. This l accomplish by a iurther embodiment of the characteristics outlinecl in Q. The net torque curve of the characteristics of the curve T'Cset forth can he clerivecl from the same aerofoil section With number of its relations of the axis line AA to the center of pressure travel The net torque tor a given angular movement is the smaller the nearer the axis line to the line center of pressure travel, for the simple reason that the eilective lever arni airrush forces is smaller. other Words, the pitching moments are smaller ancl net torque, which is but the tlitlerence between the pitching inoments of L, rnust he smaller The net torque losing smaller the magnitude of the forces introduced loy the play that torque in the system at large must he smaller,

My invention contemplates deriving the net torque thru a location of the aileron axes as near to point ct extreme torvvarc"; travel of the center of pressure as is consist cut with the deriving ot sufiicient torque, {at} to overcome friction, {in} to overcome inertie, (a) to overcome the clamping action of vanes N N and to secure that rapidity of response which the relatively high speed of action 03E gusts requires prompt and lull counteraction. This last named reouisite is dependent in a large measure upon the overcoming o" inertia, inasmuch as acceleratiou vis clirect y clepentlent upon These factors vary of course hut nevertheless hear a fairly tlefinite relation the size of the aeroplane, The amount aileron surface required in machines of average speecl, say from 80 miles per hour, averages about percent, ancl the Weight per square foot of such surfaces is suhstantially a lixecl minimum in gcocl olesig'i, The ag gregat/e opposing torques of all these factors together, however, is relatively small as comparcrl with the total net torque which can he developed thru the ailerons themselves, being only a few percent, Thus I may rerluce this phase of invention to geometrical by stating it consists in the lo cation of the axes of the ailerons in the region oi. that cncl of'the range of axes loca tions Within which net toruue curve at the form shown l ig. can he developed, which encl' lies tovvarfl the trailing cries of the aeroitoil, in the eniliorlirnent illu tratetl this range may he saiol to he about 2? percent the choral from the leacling etlge. lhe axis line is located at 25 percent ot the chord, If it were locaterl at 52'? giercent oil the chorcl insufiicient net torque Woulcl he developed to meet the encls my invention. ll it were locatecl at 28 percent of the chorcl there 'ivoulclinot he clevelopecl the net torque curve of the characteristics of my inve tion, the percent point lying; outsicle were lilo

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llltl quential.

located at 10 percent of the chord or 5 percent of the chord, the magnitude of the forces generated in the system would be extremely great and the ends of this base of my invention would be defeated. at a point between 20 and 25 percent of the chord is found to give excellent results in the case of the section illustrated.

By this invention I not only reduce the friction and enhance the ease of control, but also very greatl reduce the necessary mass of the weight Il and the size of the vanes N N and thus save a great deal of weight. Sinceby keeping the magnitude of the airrush',.torques at this prescribed minimum, the torques of gravity and the side pressure torquesrequired to co-act with them, are correspondingly smaller. Yet in attaining these ends accuracy of response of the system, deadbeat action, range of effective control, and sufliciency of control, have in nowise been sacrificed since other characteristics of the system remain the same.

The system is extremely adaptable. It may be applied to existing aeroplanes with out substantial alteration, merely by removing the usual ailerons and mounting the ailerons prescribed by these inventions. They may be used conveniently in place of.

the usual overhang. They are applicable to all types of planes. Embodied in new aeroplanes the additional expense is inconse- The usual control mechanisms are not changed. The usual interconnecting cables are used. The weight moving as it does in a horizontal plane may be mounted beneath a false floor in any cockpit. There are many suitable locations for relatively small vanes N, N.

The system is likewise capable of many modifications. In Fig. 3, I show one of these. Note firstly that vanes N and)? are consolidated and placed on the tail of the ma chine with the rudders. I Note secondly,

. that this vane is directly connected with the lever E in such mi inner as to be operated from that lever instead of from the branch C, C of the cable. As before, the weight W is located in advance of the center of gravity of the machine and by reason of its location on the tail the vane surface N N is well aft of the CG. Like the system of Fig. 1 the rudder bar ma or may not carry the pivot of the lever u, so that when a turn is attempted there may or may not be initial banking of the machine due to movement of the ailerons directly from movement of therudder bar. Movement of the ailerons to bank the craft is enhanced by virtue jointly of the fact that weight W is located forward of the center of gravity and vane N is located so very far aft. lows from the fact that the initial movement of the craft in response to operation of the rudder bar is to move around its center of location This folgravity. In such movement the inertia of weight W causes it to lag behind, and such movement itself generates a side pressure on N N, which side pressure is the greater because of the greater resultant velocity of the airrush incident to the location of N, N? so far removed from the axis of rotation of the aeroplane. Still further when located on the tail of the craft surface N N acts as a rudder would act to counteract differences in drag occasioned by differential movement of the ailerons. Thus when ailerons R is lowered and aileron L is raised there is a greater drag 011 the side of aileron E. This is counteracted by the coordinate movement imposed by'N N Thus too, when the rudder bar carries lever E, there is a momentary let off when makin which gives the machine time to without substantial skidding.

In Fig. 4 is shown an application to ailerons of the usual type. Aileron 11 in Fig. 4 is a trailing edge aileron of the Handley- Page type which is intended to be substantially fully balanced aero-dynamically along its own axis. Connected to that axis, or directly to the balanced aileron, and projecting from the end of the machine, is a controlling aileron R having the section axis location, and other characteristics of the ailerons R and L, of.my invention. Such controlling aileron need be relatively small as compared with ailerons R and L in the system of Figs. 1 and 3, since it need not develop so great corrective torque of itself. Cables C and C are connected to a weight W and vane surface N, N and the control mechanisms as in the case of Figs. 1 and 3.

In Fig. 5 is shown an application thru a combination of the Handley-Page balanced type of aileron and the German superposed balancing plane. As. in case of Fig. 4, I propose that the trailing edge aileron be perfectly balanced aero-dynamically. The superposed surface, however, connected with the balanced ailerons by suitable horns, will be given the characteristics of the ailerons R and L, of Figs. 1 and 3, so that they will be the controlling elements of the system. The .cable connections are intended to be the same.

zany type of aileron whatsoever may be use The system may be utilized in the form of pilot controls to overn any of the usual types of ailerons t ru ap ropriate servomotors or equivalent modi cations. When so used inertia and friction may be reduced to a veritable minimum, and promptness, fullness and accuracy of response realized to the full. For very large machines the servomotor system may be preferred to the direct acting system despite the added complication occasioned by the servo-motor itself. And there are yet other modifications,

ank up a turn in the annexed claims I aim to define my in.- vention as applied thru any and all embodiments in its generic spirit,-

What is claimed is: p

a 1., An aircraft comprising a main supporting member which constitutes the lifting body of the craft, a balancing device upon each side of said main supporting member and presenting co-operating surfaces arranged to be normallycontinuously acted upon in flight by air pressure to produce torques in opposite directions about the longitudinal axis of the craft, said balancing devices being connected to each other and each responsive to temporarily preponderating pressure-thereon to increase the torque of the other, and a vane connected with said balancing devices and acted upon by the air rush when the aeroplane develops lateral acceleration to move the balancing devices in a direction to decrease the lateral acceleration.

2. An aircraft comprising a main sup porting member which constitutes the lifting body of the craft, a balancing device upon each side of said main supporting member and presenting cooperating surfaces arranged to be normally continuously acted upon in flight by air pressure to produce torques in opposite directions about the longitudinal axis of the craft, said balancing devices being connected to each other and each responsive to temporarily preponderating pressure thereon to increase the torque of the other, and a vane, the body of which is located aft of the center of gravity ot the aircraft, connected with said balancing devices and acted upon by the air rush when the craft develops lateral acceleration to move said balancing devices in a direction to counteract said lateral acceleration.

3. An aircraft comprising a main supporting member which constitutes the lifting body of the craft, a balancing device upon each side of said main supporting member and presenting cooperating surfaces arranged to be normally continuously acted upon in flight by air pressure, to produce torques in opposite directions about the longitudinal axis of the craft, said balancing devices being connected. to each other and each responsive. to temporarily preponderatpressure thereon to increase the torque of the ot ier, but acted upon through gravity the craft is unbalanced to iurther in crease the torque, together with a vane concted said balancing devices and acted c son by air rush when the aeroplane de lopes lo" l acceleration in a direction to .ove sails novices to counteract said devel- 7 n a main sup on constitutes the littbalancing device supporting in flight by air pressure, to produce torques in opposite directions about the longitudinal axis of the craft, said balancing devices being connected toeach other and each respone sive to temporarily preponderating pressure thereon to increase thetorque ofthe other, and a weight located in advance of the vertical axis of rotation of said craft, connected with said balancing; devices and acted upon by gravity when the craft is unbalanced to tend to move the balancing devices in a direction. to decrease the degree of unbalancing.

5. An aircraft comprising a main supporting member which constitutes the lifting body of the craft, a balancing device upon each side of said mainsupporting member and presenting cooperating surfaces arranged to be normally acted upon in flight by air pressure to produce torques in opposite directions about the longitudinal axis of the craft, said balancing devices being connected to each other and each responsive to temporarily preponderating pressure thereon to increase the tor us of the other, and a wei ht located in a vance of the vertical axis ot rotation of said craft, connected with said balancing devices and acted upon by gravity when thecrait is unbalanced to tend to move the balancing devices in a direction to decrease the degree out unbalancing, and a vane, the body of which is located aft of the center of gravity oil the craft, connected with said balancing devices and acted upon by the air rush when the craft develops lateral acceleration. to move said balancing devices in a direction to counteract said lateral acceleration,

6. A balancing system for aircraft comprising a pair of transversely pivoted and interconnected aero-dynamically dilderential self-acting lateral balancing surfaces, one on each side of the plane of symmetry and having normally equal and substantial angles of incidence, said balancing surfaces being of such aerotoil section that their net torque about their transverse ivotal' axes progressively increases when tiey are displaced from their normal positions or equal incidence, throughout their required. range of BJQ GCtlVQ operation.

Y, A balancing system for aircraft comprising a pair of transversely pivoted and interconnected aero-dynamicaily differential self-acting lateral balancing surfaces, one on each side of the plane of symmetry and having normally equal subs angles incidence, said balancing sur 1 being or such aerotoil section that their net torque about their transverse pivotal ares pro ssiv" i creases w on they e disoir normal positions equal onghout their required ttflgb not till

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of effective operation and irrespective of the location of the pivotal axes with re spect to the forward travel of the center of pressureof the section within a determinate range.

8. A balancing system for aircraft comprising a pair of transversely pivoted and interconnected acre-dynamically differential self-acting lateral balancing surfaces, one on each sideof the plane of s inmetry and having normally equal an substantial angles of incidence, said balancing surfaces being of such aerofoil section that their net torque about their transverse pivotal axes progressively and uniformly increases when they are displaced from their normal positions of equal incidence, throughout their required range of effective operation.

9. A balancing system for aircraft comprising a pair of transverselypivoted and interconnected acre-dynamically differential self-acting lateral balancing surfaces, one on each side of the plane of symmetry and having normally equal and substantial angles of incidence, said balancing surfaces being of such aerofoil section that. their net torque about their transverse pivotal axes progressively increases'when they are displaced from their normal positions of equal incidence, throughout their required range of effective operation and irrespective of the location of the pivotal axes with respect to the forward travel of the center of'pressure of the section within a determinate range, and transverse pivotal axes for said surfaces located within and in the vicinity of the rear end of said range.

10. A balancing system for aircraft comprising a pair of transversely pivoted and interconnected acre-dynamically differential self-acting lateral balancing surfaces, one on each side of the plane of symmetry and having normally equal and substantial angles of incidence, said balancing surfaces being of such aerofoil section that their net torque about their transverse ivotal axes progressively increases When they are displaced from their normal positions of equal incidence, throughout their required range of effective operation, and a standard of position with respect to earth connected to said balancing devices both to actuate and be actuated by the same.

11. A balancing system for aircraft comprising a pair of transversel pivoted and interconnected acre-dynamically differential self-acting lateral balancing surfaces, one on each side of the plane of symmetry and having normally equal. and substantial angles of incidence, said balancing surfaces being of such aerofoil section that their net torque about their transverse pivotal axes progressively increases when they are dislaccd from their normal positions of equal incidence, throughout their required range of effective operation, and a standard of position with respect to earth connected to said balancing devices both to actuate and be actuated by the same, which standard develops a progressively increasing gravity torqueas the craft rolls, throughout the required range of effective operation of said balancing surfaces. A

12. A. balancing system for aircraft comprising a pair of transversel pivoted and interconnected areo-dynamica ly differential self-acting lateral balancing surfaces, one on each side of the plane of symmetry and having normally equal and substantial angles of incidence, said balancing surfaces being of such aerofoil section that their net torque about their transverse pivotal axes progressively increases when they are displaced from their normal ositions of equal incidence, throughout 1; eir required range of effective operation, and a horizontally swinging pendulum connected with said balancing devices both to actuate and be actuated by the same.

13. A balancin system for aircraft comprising a pair 0 transversel pivoted and interconnected acre-dynamically differential self-acting lateral balancing surfaces, one on each side of the plane of symmetry and having normally equal and substantial angles of incidence, said balancing surfaces being of such aerofoil section that their net torque about their transverse pivotal axes progres sively increases when they are displaced from their normal ositions of equal incidence, throughout t eir required range of effective operation, and a standard of posi tion'with respect to earth, and a vertically pivoted vane subject to side pressure bot connected to said balancin devices to actuate and to be actuated by the same.

14. A balancing system for air craft comrising a pair of transversel pivoted and interconnected acre-dynamically differential self-acting lateral balancing surfaces, one on each side of the plane of symmetry and having normally equal and substantial angles of incidence, said balancing surfaces being of such areofoil section that their net torque about their transverse pivotal axes increases progressively when they are displaced from normal positions of equal incidence throughout the required range of effective operation irrespective of the normal incidence as imposed by the adjustment of the flying angles of the craft.

15. In an aircraft, a pair of transversely pivoted and interconnected aero-d manncally differential self-acting lateral )alancing surfaces, one on each side of the plane of symmetr and having normally equal and substantial angles of incidence, of an acrefoil section developing a progressively increasing net torque a out their transverse pivotal axes when displaced from normal po 5] Lie?) sitions of equal incidence throughout a range of such. positions at least equal to the range 0t flying angles of the airplane.

16. in an aircraft, a lateral balancing surface mounted on a transversely extending pivotal axis and having a normal positive and substa'ntialangle oi? incidence having torque about its transverse pivotal axis increasing regularly over a determinate range of removal of its pivotal axesgtorward from the position of extreme forward travel of the center of pressure, and a transverse pivotal axis for said surface within and nearer the after than the forward end of said range.

17. A lateral balancing system for aircraft comprising a pair of interconnected aerodynamicallydifferential ailerons, one on each side of the plane of symmetry and having normally equal and substantial angles of incidence developing a differential and progressively increasing net air rush torque about their axes, a weight arranged to shift when the craft rolls and connected to actuate and be actuated by the ailerons and develop-l ing ,a gravity torque when the craft rolls, and a vertically disposed vane responsive to side air rush and connected to actuate and be actuated by said ailerons and developing a side pressure air rush torque, the relative magnitude of the maximums of said torques being as follows: that of the vane being sutlicient merely to overcome friction and inertia and to precess the system at large to movement in the proper direction, that of the weight being suiiicient to overcome triction, inertia, and the vane torque, and to operate the ailerons against normally developed air rush torque a degree less thantheir full degree, and that of the ailerons under gusts being sutlicient not only to overcome friction, inertia and the Vans torque, but also to deflect the ailerons to their fullest extent. v

18. A lateral balancing system for air craft comprising a 1 air of interconnected aero dynamically di 1 erential ailerons, one on' each side of the plane of symmetry and having normally equal and substantial angles of incidence developing a differential and progressively increasing net torque about their axes, and a weight arranged to shift when the craft rolls and connected to actuate and be actuated by said ailerons and devel- 0 ing a gravity torque when the craft rolls, t e relative magnitude of the maximums of said torques being as follows: that of the weight being suthcient to overcome the triction and inertia of the'system at large, and

weaves also move the ailerons against their net torque a degree less than the full extent, and that of the ailerons being sufficient not only to overcome the friction and inertia of the system at large but also to deflect the system-to its fullest extent.

19. A lateral balancing system for aircraft comprising a air of interconnected aero-dynamically di rerential ailerons, one on each side of the plane of symmetry and having normally equal and substantial angles of incidence developing a difierential and progressively increasing net torque about their axes, a weight arranged to shift when the craft rolls and actuating and actuated by said ailerons and developing gravity and centrifugal force torques, and a vertically disposed vane mounted to be shifted by side air rush, also connected to actuate and be actuated by said ailerons and developing damping and side pressure torques, the relative magnitude of the maximums of said torques being as follows: those of the ailerons predominant, those oi the weight subordinate thereto, and those ot the vane in turn subordinate to those of the weight.

20. A lateral balancing system for aircraft comprising a pair of interconnected aero-dynainically ditierential ailerons, one on each side of the plane of symmetry and having normally eqiial and substantial angles of incidence developing a diflerential and progressively increasing net torque about their axes, a weight arranged to shift when the craft rolls and actuating and; actuated by-said ailerons and developing gravity and centrifugal force torques, and a vertically disposed vane mounted to be shifted by side air rush, also connected to actuate and be actuated by said ailerons and developing damping and side ressure torques, the relative magnitude 0 the maximums of said torques being as follows: those of the air rush torque being sufficient to overcome the friction and inertia of thesystem at large, to overcome the vane torque and additionally to attain full deflection of the system, those ot' the weight acting in conjunction with those of the ailerons but while sufficient to overcome the inertia and friction of the system at large insuilicient to carry the aileron and vane to full deflection, and those of the vane sufficient to overcome friction and inertia but suflicient to move said ailerons to a less degree than said weight.

lln testimony whereof l hereunto aliix'iny signature.

' JQHN 1P. TARBOX.

till

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